DELTA-M, VERTICAL COMPONENT, AND MEDIA NOISE OF NIP-UNDERLAYER AND CR-UNDERLAYER MEDIA FOR LONGITUDINAL RECORDING

Media having Cr-underlayer and NiP-underlayer were compared using transmission electron microscopy (TEM), delta-M, torque (vertical component), and media noise measurements. TEM micrographs show that NiP-underlayer media were more isolated than Cr-underlayer media. Of the Cr-underlayer media, CoCrTa media seem to exhibit grain isolation. The grain size of NiP-underlayer media was smaller (30 nm) than that of Cr-underlayer media (60 nm). Results indicate that media with isolated grains seem to have higher vertical component than media with more continuous grains. The NiP-underlayer media exhibits lower media noise than the Cr-underlayer media. This is attributed to smaller and more isolated grains in the NiP-underlayer media.